The present invention relates to condensation lines or cold-water drain lines. More particularly, the invention relates to the prevention of clogging or plugging of such lines by growth of cold-water algae or bacteria.
Condensate is formed in all refrigeration systems. This condensate is formed by warm moist air being forced over the cold coils of the evaporator. The evaporator is located in the attic space in most homes. Removing this condensate has always presented many problems. The condensate can be removed in several ways. It can be piped to the outside. This is not an option for most homes because of unit placement and roof design. Another way is to pipe to a sewer vent line in the attic, thereby piping the condensate to the sewer system. The drawback of this second method is that the condensate must be piped through a plumber's trap, commonly known as a P-trap. A P-trap must be installed to prevent sewer gases from being drawn into the living space of the home by the suction of the evaporator fan. P-traps are notorious for plugging due to the small flow going through the trap, and due to the attic temperature, both of which promote growth of cold-water algae. When the P-trap becomes plugged, the flow of condensate stops. A secondary drain pan is a requirement of the plumber's code in most if not all areas. The pan is located beneath the evaporator. The pan catches and holds the condensate, or sends the condensate out a secondary drain line. If the condensate is held in the drain pan, a safety shut-off switch, located in the pan, stops the air-conditioner unit. The ability to stop the unit depends on several things, pan installation and condition being the most important. If either is not right, the condensate could drain from the unit onto the ceiling, which causes at least water spots and at worst a ruined ceiling. If the switch stops the unit, the living space is not being cooled. In order for the air conditioner to restart, the P-trap must be unplugged and the secondary drain pan emptied. This is usually done by a service technician on a service call. It is accomplished by disconnecting or cutting the drain line, blowing the plug out, flushing the pipe, and reconnecting. Depending on the unit, the attic temperature, and the quality and time of the last cleaning, this condition can occur two or three times in a normal cooling season.
There have been numerous devices patented which deal with the problem of plugging of drain lines by algae/bacterial growths. Most of these patents teach cleaning the line after a plug has formed and stopped water flow.
There are few patented devices that could be used to prevent the formation of a plug in a drain line. U.S. Pat. Nos. 6,701,740 and 5,402,813 disclose two such devices. The devices are installed in the condensate drain line downstream of an evaporator. If a chlorine-releasing tablet were used with these devices, chlorine gas and/or a chlorine-water mixture/solution could and probably would back-migrate into a condensation line to a cooling unit to which the condensation line is connected. Some units have a plastic tray under the evaporator coil. Unfortunately, the plastic from which the tray is made breaks down over time and leaks. Both chlorine and hydrochloric acid are corrosive. If the chlorine and the water should form hydrochloric acid, both the chlorine and the acid would then attack the sheet metal of the unit, and the result would be catastrophic.
U.S. Pat. No. 6,895,771 discloses a device for recycling the condensate in the drain line for reuse. There are two P-trap-like fittings on the inlet of the device. There is nothing to keep these fittings from plugging by algae/bacteria-promoting growths. Moreover, a check valve included in the device would also be subject to such plugging.
U.S. Pat. No. 5,402,813 to Keen discloses an in-line chlorinator for a condensation line. A first disadvantage of the in-line chlorinator disclosed by Keen is that it requires a separate P-trap in the drain line. A second disadvantage is that chlorine, hydrochloric acid, and/or gases from a sanitary sewer line can migrate back through the inlet and the condensation line to a cooling unit to which the condensation line is connected. The present invention provides a solution to both of these problems